Weak signal to no wifi signal within steps from strong signal

See -> Recommended settings for Wi-Fi routers and access points

Recommended settings for Wi-Fi routers and access points - Apple Support

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Weak security settings to avoid on your router

Don't create or join networks that use older, deprecated security protocols. These are no longer secure, they reduce network reliability and performance, and they cause your device to show a security warning:

• WPA/WPA2 mixed modes
• WPA Personal
• WEP, including WEP Open, WEP Shared, WEP Transitional Security Network, or Dynamic WEP (WEP with 802.1X)
• TKIP, including any security setting with TKIP in the name

Settings that turn off security, such as None, Open, or Unsecured, are also strongly discouraged. Turning off security disables authentication and encryption and allows anyone to join your network, access its shared resources (including printers, computers, and smart devices), use your internet connection, and monitor the websites you visit and other data transmitted over your network or internet connection. This is a risk even if security is turned off temporarily or for a guest network.

See also -> If you need help with your Wi‑Fi password

If you need help with your Wi‑Fi password – Apple Support (UK)

•  You need to sign in to your router.
• The Wi-Fi network name, or SSID (service set identifier), is the name your network that has a password.

or If you have iOS 16 / iPadOS 16:

Go to -> Settings -> tap Wi-Fi -> tap on the hidden Password -> enter Passcode -> you will then see the Wi-Fi Password.